in jshint-server/src/server.ts [619:627]
private getMessage(err: any, document: TextDocument): string {
let result: string = null;
if (typeof err.message === 'string' || err.message instanceof String) {
result = <string>err.message;
} else {
result = `An unknown error occured while validating file: ${Files.uriToFilePath(document.uri)}`;
}
return result;
}